title: Simulated microgravity conditions and carbon ion irradiation induce spermatogenic cell apoptosis and sperm DNA damage.
abstract: OBJECTIVE
  To investigate the effect of simulated microgravity and carbon ion irradiation (CIR) on spermatogenic cell apoptosis and sperm DNA damage to the testis of male Swiss Webster mice, and assess the risk associated with space environment.
  
  
  METHODS
  Sperm DNA damage indicated by DNA fragmentation index (DFI) and high DNA stainability (HDS) was measured by sperm chromatin structure assay (SCSA). Apoptosis of spermatogenic cells was detected by annexin V-propidium iodide assay. Bax (the expression levels of p53) and proliferating cell nuclear antigen (PCNA) were measured by immunoblotting; p53 and PCNA were located by immunohistology.
  
  
  RESULTS
  HDS, DFI, apoptosis index, and the expression levels of p53 and Bax were detected to be significantly higher in the experimental groups (P<0.05) compared with those in the control group; however, the PCNA expression varied to a certain degree. p53- and PCNA- positive expression were detected in each group, mainly in relation to the spermatogonic cells and spermatocytes.
  
  
  CONCLUSIONS
  The findings of the present study demonstrated that simulated microgravity and CIR can induce spermatogenic cell apoptosis and sperm DNA damage. Sperm DNA damage may be one of the underlying mechanisms behind male fertility decline under space environment. These findings may provide a scientific basis for protecting astronauts and space traveler's health and safety.
authors.affiliation: Department of Heavy Ion Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, Gansu, China; Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou 730000, Gansu, China; Key Laboratory of Heavy Ion Radiation Medicine of Gansu Province, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Hong Yan
authors.initials: HY
authors.lastname: Li
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
authors.forename: Guo Ying
authors.initials: GY
authors.lastname: Miao
authors.forename: Yi
authors.initials: Y
authors.lastname: Xie
authors.forename: Chao
authors.initials: C
authors.lastname: Sun
authors.forename: Cui Xia
authors.initials: CX
authors.lastname: Di
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.forename: Yuan Yuan
authors.initials: YY
authors.lastname: Liu
authors.forename: Xin
authors.initials: X
authors.lastname: Zhang
authors.forename: Xiao Fei
authors.initials: XF
authors.lastname: Ma
authors.forename: Shuai
authors.initials: S
authors.lastname: Xu
authors.forename: Lu
authors.initials: L
authors.lastname: Gan
authors.forename: Xin
authors.initials: X
authors.lastname: Zhou
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000528:radiation effects; D002244:Carbon; D049109:Cell Proliferation / Q000528:radiation effects; D004249:DNA Damage; D020450:Heavy Ions / Q000009:adverse effects*; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D011897:Random Allocation; D013076:Sperm Count; D013091:Spermatogenesis / Q000528:radiation effects*; D013094:Spermatozoa / Q000528:radiation effects*; D013737:Testis / Q000528:radiation effects*; D018474:Weightlessness Simulation
chemical_list: D002244:Carbon
keywords: Carbon ion irradiation; Simulated microgravity; Sperm DNA damage; Spermatogenic cells apoptosis